Closing application after pressing back button, not returning to previous activity

problem:

Working scenario: I have a MainMenuActivity and when i start another activity and press Back Button it return to previous activity,but...

Problem scenario: When I start Activity B, from Activity A, and then press Home button and i after few seconds back to application, and then press Back button application is closed/minimalized. But i want after minimalized application can go back to Activity A.

Any idea how to do it?

via Chebli Mohamed